/ MINIMAL PDP-8 BOOTSTRAP PROGRAM (RX) / / Taken from a manual for an 8/e disk subsystem built by DSD; / shorter and easier to toggle in than DECs bootstrap. / The following is a minimal length boot program for both / the RX01 and RX02. This boot tries only the specified / drive with the specified density. Start at location 32 to / BOOT drive 0. Start at location 22 to boot drive 1. / This has been verified to work with an OS/8 diskette. / the contents of locations 60 and 61 can be fudged to / change what disk and what density are used. / configuration section IOTADR=0750 / default system drive is at IOT 75 DRIVE0=0000 DRIVE1=0020 DRIVE=DRIVE0 / set to either DRIVE0 or DRIVE1 SINGLE=0000 DOUBLE=0400 DENSTY=DOUBLE / set to either SINGLE or DOUBLE / RX01 and other opcode definitions LCD=6001+IOTADR XDR=6002+IOTADR STR=6003+IOTADR SDN=6005+IOTADR NL001=CLA CLL IAC NL002=CLA CLL IAC RAL NL006=CLA CLL CML IAC RTL / THIS SECTION IS NEEDED ONLY WHEN BOOTING FROM DRIVE 1. / READS IN SECTOR 1 TRACK 1 ON DRIVE O OR 1. / DOES NOT USE LOCATIONS 22-31 WHEN STARTED AT 32 / START HERE TO BOOT DRIVE 0 (ASSUME MASTER CLEAR HAS / READ DRIVE 0 TRACK 1 SECTOR 1 FOR YOU). *32 BOTDV0, NL002 / MAKE EMPTY BUFFER COMMAND CHKFLG, SDN / WAIT FOR DONE FLAG UP JMP LOAD+1 / NO - CHECK FOR READY TRANSFER TAD UNIT / YES-PUT IN READ UNIT, DENSITY LCD / SEND EMPTY BUFFER COMMAND JMP BOTLP / START TO LOAD SECTOR BUFFER *47 ///////////////// BOTLP, JMS LOAD / READ NEXT WORD FROM SILO DCA 2 / START LOADING AT LOC. 2 ISZ .-1 / BUMP LOAD ADDRESS JMP BOTLP / CONTINUE EMPTYING BUFFER / LOAD, .-. / DATA TRANSFER SUBROUTINE STR / SKIP IF CONTROLLER WILL SPEAK JMP CHKFLG / NO - CHECK IF FINISHED XDR / TRANSFER DATA IN OR OUT JMP I LOAD / RETURN TO CALLER / 7004+DRIVE / USED BY SECONDARY BOOT / TO SELECT DRIVE 0 OR DRIVE 1 UNIT, DENSTY+DRIVE / WHAT TRANSPORT, WHAT DENSITY? $